During the 1970's radiological imaging systems were developed to assist surgeons in ascertaining the internal condition of a patient in greater detail. Specifically, computer assisted tomography (CAT) systems were developed to enhance images generated from data produced during a radiological scan of a patient. The patient is placed within a gantry, and a radiation source and radiation detectors are positioned opposite one another to be rotated about a portion of the patient's body. The data generated by the radiation detectors are utilized by a computer to generate radiographic images or "slices" of the body position to give a doctor greatly enhanced views through the area of interest.
Later radiographic imaging systems included magnetic resonance (MRI) and positron emission tomography (PET) imaging which generate images from energy sources that do not use x-rays or the like. These devices are useful because they provide different or additional information about organs or tissues than CAT scan images. In this application the term scanners refers to imaging devices regardless of the technique utilized to generate the images.
Surgery may be performed to investigate, repair, or remove anomalies located within the body of a patient. Normally, the only presurgery access to the body available to a surgeon is through images generated by an imaging system. Techniques are known which may be used to identify the location of a lesion or injury within the brain or other portion of the body. In addition, it is often critical to determine a suitable pathway through the brain or body to access that location in order to minimize damage to the intervening tissue. Thus, identifying the pathway to the site may be almost as critical as identifying the site itself, and systems have been developed that are capable of utilizing scanned patient data at a later time and at a different location, for example, in an operating suite.
Such stereotactic systems must first match or co-register the scanned data to the patient. Co-registration is a process by which a computer matches fiducials associated with image data to fiducials associated with the patient's body. The image fiducials are typically selected by using a mouse and cursor to identify on a displayed image points that lie on a patient's skin. An articulated arm and probe are coupled to the computer to provide coordinate data for points external to the computer. Using the arm and probe, the user selects points on the patient that correspond to the selected image fiducials and the computer executes a program that matches the corresponding points. After a sufficient number of points have been selected (usually at least 8), the computer may identify the point in the displayed images that corresponds to the position of the probe proximate the patient's head. Such a system is made by Radionics of Brookline, Mass. and is identified by its product name The Operating Arm.
Such a system provides "navigational" information to a surgeon, that is, the surgeon may bring the probe to a particular location on or within a patient's body and have that location identified on the displayed image. In this way, the surgeon may view areas on the displayed image and determine their proximity to the probe location. In that manner, the surgeon may confirm the surgical approach to a target. Such systems, using an invasive skull ring or a noninvasive probe holder are able to locate, project and display a stabilized image of the surgical path prior to a surgical procedure being performed.
The above systems were initially designed to facilitate intracranial surgery, and therefore, the articulated arm and noninvasive probe holder are coupled to a skull clamp in which the patient's head is mounted. While such a system has proven satisfactory for many neurosurgical procedures, the physical arrangement of equipment has proven to have some limitations. For example, the articulated arm and probe holder extending from one side of the skull clamp provides excellent access to the upper portion of the skull. However, as the area of interest extends toward the lower portions of the skull and upper portions of the spine, the range of orientation of the articulated arm at its more extended positions becomes smaller and limited. Further, with known systems, as the arm of the probe and tool holder is cantilevered from its support; and as it extends out to its longer positions, it becomes less rigid and subject to motion and changes of position from an inadvertent knock or bump.
Therefore, there is a need for a tooling support system that has a greater range of motion, is preferably adjustable, preferably provides transportation for the articulated arm and probe and is very stable regardless of its position and orientation.